Deflection yoke



Jan. 17, 1967 c. E. TORSCH DEFLECTION YOKE 4 Sheets Sheet 1' Filed Oct.v22, 1962 Fj- 5 PRIOR ART PRIOR ART INVENTOR. CHHRLes E TORSCH TTORNEVS#9 7,1 QETORSCH 9 9,299,379

DEFLECTION YOKE Filed Oct. 22, 1962 4 Sheets-Sheet 2 PRiOR ART INVENTOR.Cnmuas E. TORSCH gal/Le, 1 TUE Jain. 17, 1967 c. E. TORSCH DEFLECTIONYOKE 4 Sheets-$heet 3 Filed Oct. 22. 1962 INVENTOR. CHHRLES E Tonscuqaae, Tana TToRNEvs Jan. 17, 1967 Filed Oct. 22, 1962 (LE. TORS'CHDEFLECTION YOKE 4 Sheets-Sheet INVENTOR. CHFIRLES E. Torkscn TTORNEYSUnited States Patent Filed Oct. 22, 1962, Ser. No. 231,890 24 Claims.(Cl. 335-213) The present invention relates to cathode ray tubedeflection devices, and more particularly to novel toroidalelectromagnetic deflection coils for use with cathode ray tubes.

During the operation of a cathode ray tube, the cathode ray beam iscontinually deflected so as to trace a pattern, known as a raster, onthe tube screen. The deflection is caused by passing the beam through atime-varying magnetic field which emanates from deflection coils mountedabout the tube neck.

In order to prevent deflection defocusing at the periphery of theraster, it is generally desirable that the field generated by the coilsbe uniform andmore intense at the beam entry end of the deflection yoke.is usually achieved by the use of deflection coils having a cosinedistribution. However, where .the cosine distribution is used in wideangle deflection, a further ditficulty arises. Since, in wide angledeflection the radius of curvature of the screen is usually much greaterthan the average distance from the center of the yoke to the screen, theraster collapses at the edges so that it is shaped like a pincushionrather than being rectangularas desired.

This type of distortion is usually compensated for by the use ofadditional elements, known as anti-pin-cushion magnets, which aregenerally positioned on a non-magnetic frame attached to the deflectionyoke near the flare of the picture tube. The magnets serve to pull orstretch the raster into the desired shape. Such an arrangement is notonly costly, but in certain applications, such as in color three guntube arrangements, the use of pin-cushion correction magnets isundesirable as it creates color blemishes.

Moreover, the prior art windings utilized large amounts of copper,required more space within the core for the copper, and simultaneouslyconsumed more power.

Accordingly, it is an object of this invention to provide a novel typeof deflection yoke winding and coil arrangement which in itselfdecreases the distortion of the raster at its periphery and therebyminimizes the need for pincushion magnets for correcting such imagedistortion.

A further object is to provide a novel type of winding to create amaximum flux density with favorable distribution in the yoke region witha minimum of copper for the winding and minimum power consumption.

Another object is to provide a novel winding which decreases the energylosses during the deflection process, and enables the internal diameterof the core structure to be narrowed, and which causes a decrease in theenergy storage in the quadrature windings.

A further object is to develop a winding for use in color televisionyokes for decreasing pin-cushion distortion where is it undesirable touse anti-pin-cushion magnets due to their creation of color blemishes.

Briefly, the foregoing objects are accomplished by the use of a toroidalcoil having windings thereon wound in a tilted manner. Referring now tothe drawings:

FIG. 1 is a cross-sectional elevation of a yoke assembly taken at 45 tothe axis of the horizontal and vertical flux;

FIG. 2 is a cross-sectional elevation view of a right conical corehaving a prior art radial winding thereon;

FIG. 3 is a front view of the assembly of FIG. 2;

FIG. 4 is a cross-sectional elevation view of a right conical corehaving a tilt-ed winding thereon;

FIG. 5 is a front view of the assembly of FIG. 4;

This condition 3,299,379 Patented Jan. 17, 1967 FIG. 6 is across-sectional elevation view of a combined conical and cylindricalcore having a prior art radial winding thereon;

FIG. 7 shows the core of FIG. 6, but with a tilted winding thereon;

FIG. 8 schematically shows a method of constructing a tilted winding;

FIG. 9 is a cross-sectional elevation of a curved-flare core having atilted winding thereon; v

FIG. 10 is a front view of the assembly of FIG. 9;

FIG 11 is a front view of a core segment having an inverse tiltedwinding thereon.

Deflection coils are either of saddle or toroidal shape. The toroidalcoil is one which is wound axially of the core, circumscribing at leasta portion of both the inside and outside thereof. The saddle type coilgenerally fits adjacent only one side of the core. A deflection yoke mayuse either saddle coils, toroidal coils, or a combination thereof. Thepresent invention relates to yokes wherein at least one of the coilsutilized is toroidal.

Referring again to the drawings, FIG. 1 shows a deflection yoke 20mounted on the neck 21 of a cathode ray tube 22 adjacent the flared orbulb portion 23 of the tube. The yoke includes a pair of saddle-typehorizontal deflection coils 26 positioned adjacent the neck of the tube,an insulator 27 placed about the horizontal coils, and a ferromagneticcore 28, having a toroidal coil pair 30 wound thereon, placed about theinsulator intermediate the front 31 and rear 32 flanged portionsthereof.

As shown in FIG. 1, the toroidal coil pair comprises a pair ofoppositely disposed coil halves 34 and 35. Each coil half is woundaxially of the core in a toroidal fashion and extends peripherally onlyalong a portion of the core,

as shown, for example, in FIG. 2.

In order to permit wide angle deflection, cores are generally flared,the cores being smaller in internal dimension at the rear, i.e. the beamentrance end 37 of the core and larger in internal dimension at thefront, i.e. beam exit end 38 of the core. This flaring permits the frontend 39 of each coil half to be positioned upon the bulb portion 23 ofthe tube thereby enhancing the wide angle deflection. The coresgenerally have a front face 24 and a rear face 25 which separate theoutside surface 46 of the core from the inside surface 47.

The flared cores may be in the shape of a regular cone as shown in FIG.4, a combined cylinder and cone as shown in FIG. 6 or curved such as thecircular flare shown in FIG. 9. v

For purposes of clarity in explaining the present invention, thewindings shown will be of much larger conductor diameter, and the turns:fewer than might be the case in actual practice wherein more turns offiner wire may be utilized. In the past as shown in FIGS. 2 and 3, ithas been the practice to wind toroids by winding each turn along theshortest axial distance, pulling the turn taut, and continuing to thenext turn. Such procedure conformed to the natural shape of the core andutilized the least length of copper. As a result of this prior art turnalignment, the portions of theturns adjacent the front 33, i.e. beamexit end, of the core were spread apart. This is shown by viewing thefront end portions 41 of the coil half 34 of FIG. 2. This is alsoapparent from me front end view, FIG. 3, wherein it is shown that theturns of the prior art winding were radially disposed relative to thecentral axis so that the planar extensions 36 ofthe turns pass throughthe longitudinal central axis 480E the core. Where such radiallydisposed windings were used in conjunction with cosine winding it wasnecessary to include large anti-pin-cushion magnets. It has been foundthat by using a novel substantially non-radial type of winding, the needfor pin-cushion magnets has been decreased,

the winding inductance increased for the same number of turns, and thecurrent through these turns decreased with a consequent increase inefiiciency. The novel winding embodies the use of increased length ofcopper winding per turn, but permits the cross-section to be decreasedand the number of turns to be decreased while still producing the sameinductance and magnetic field as the radial winding. Thus, there is asaving in both initial cost and in the cost of operation.

A deflection coil winding is generally composed of a series ofsuperimposed layers. For purposes of clarity andsimplicity in explainingthe type of winding embodying the present invention, only one layer, thefirst layer, will be described. It is to be understood that subsequentlayers could be wound in the same manner with the width of the layersfollowing conventional practice of a constant or gradient width.

FIG. 4 shows a preferred form wherein the novel windings are applied toa right conical core 28A. A characteristic of the preferred form ofnovel winding is that at least one of the turns in each layer isradially disposed. In the preferred form, the radial turn or directrixillustrate-d by turn '43 .in FIG. 4, is located intermediate thesideedges 44 and 45 of each layer.

FIG. is a front view of theright cone of FIG. 4 and illustrates themanner of tilt of the turns of FIG. 4. The side turns 49 on either sideof the radial-1y disposed directrix 43 are inclined or tilted so thattheir front end portions 41A converge from the radial. As a result, asshown in FIG. 5, the extended planes 36A of the side turns 49 passbeyond the central core axis 48A rather than passing through the centralcore axis as is the case with radially disposed turns.

In the form shown, the directrix 43 is located in the middle of thelayer and the side turns 49 are symmetrically disposed on either side ofthe directrix. It is to be understood that the directrix turn need notbe in the exact center of the coil, but might be towards one edge sothatmore turns are located on one side of the directrix than on-the other.

It is apparent frornFIGS. 4 and 5 that the front end portions 41A oftheturns are positioned close together, rather than being spaced apart aswas the case with the front end portions 41 of theradial windings ofFIG. 3.

A further characteristic of the preferred form of the tilted winding isthat the circumferential span 52A of the front end of the coil may becloser in length to the length of the circumferential span 51A of therear end of the coil than the front peripheral span 52 is to the rearperipheral span '51 of the prior art radial winding of FIG. 3. In themaximum tilt, the front coil span 52A is substantially the same as therear coil span 51A. Another way of stating this characteristic is thatthe ratio of the front coil span to the rear coil span of the tiltedwinding is nearer unity than the corresponding ratio of a radiallydisposed winding.

A still further characteristic of thepreferred form of the tiltedwinding is that azimuthal angle 0 which is measured at aperture 39A,between a longitudinal axis of the wire of the winding'49 atcorresponding inner segments of turns which are wound successively inthe general direction of coil winding advancement, has a lesser valuethan a corresponding azimuthal angle 0 which is measured at aperture 37Abetween said longitudinal axis of saidsame segments of said same turns.The azimuthal angles 0 and 0 are illustrated in FIG. 5.

The inner surface 38A at the beam exit end 39 of the core has a diameterD1 at aperture 39A and which defines a circular cross section area A1 atthe aperture 39A in a plane perpendicular to the axis 48A. At theopposite end of the core, the inner surface 38A at the beam entry end 37of the core, has a diameter D2 which is less than D1 and defines acircular cross section area A2 at the aperture 3 7A at the beam entryend 37 which is correspondingly'less'than the value'of the crosssectional area point of greatest curvature of the flare.

4. A1 at aperture 39A. Since the cross sectional area A1 is greater thancross sectional area A2, the perimetrical dimension or circumference,P1, of the inner surface 38A of the core will be greater at the beamexit end 39 than at the corresponding perimetrical dimension P2 measuredat the beam entry end 37.

FIG. 6 illustrates the prior art radial type of winding on a combinedcylinder and cone type of core.

FIG. 7 illustrates a tilted winding on such a core. The front view forFIG. 7 is the same as FIG. 5.

FIG. 8 illustrates one Way of making a tilted winding. A turn 61, shownin dotted lines may be placed approximately 150 radial degrees withreference to the vertical, as shown at angle A'of FIG. 8. Then, usingthe juncture 6 2 of the turn with the rear inside edge 65 of the core asa pivot point, the turn is pivoted while adding more wire thereto, so asto enlarge the turn, until the projected plane 36A of the turn passesbeyond the central axis 43A. For example, the turn 61 may be rotateduntil the front end portion 41A of the turn 61 is rotated until it isonly with reference to the vertical as shown by angle B in FIG. 8. Thenext wire 62 is then laid so that the turns are touching at the frontend portions 41A and at the rear end portions 71A. As the windingprogresses, one of the turns 43 is so positioned that its planarextension will pass through the central axis thereby forming adirectrix. The turns on the other side of this directrix are thenaligned symmetrically to the first laid turns with the projected planesof the turns extending beyond the central axls.

It is to be understood that in actual practice more turns than one maybe radial. However, it is preferred that at least more than half of theturns of each layer should be tilted.

Where the core has a front face 24, 24A and 248, as shown .in FIGS. 3, 5and 10, respectively, the difference between the radial windings of'FIG.3 and the tilted windings of FIGS. 5 and 10 is most apparent where theplane projection of turns method of comparison is utilized.

It is to be noted that where a curved core is machine wound, anadditional characteristic of the novel tilted windingmay appear. Asshown in FIGS. 9 and 10 the rear end portions 71A of the turns arespread apart slightly as compared to the rear end portions 71 of theprior art'radial winding of FIGS.- 2 and 3. However,

unlike the radial arrangement, the length of the front spanSZB of thecoil approaches the length of the rear span 51B, and in some cases issubstantially the same. A further characteristic of the machine woundcurved core arrangement is that the turns converge intermediate thefront and rear ends of the coil, thereby giving the coil'a slightlyinwardly bowed appearance, Thus the narrowest span of the wires is nolonger located adjacent the rear end of the core, but at a pointinter-mediate the front and rear ends of the coil. The'point ofnarrowest span, the intermediate span 56, is generally located at ornear the For example, where the'curved core has a circular flare asshown in FIG. 9, and a chord'58 is drawn intermediate the ends of thecircular segment, then the smallest span will be located at or near thegreatest sagittal distance 59 of the circular segment from the chord. Asa result, inductance is increased adjacent an important point in thepath of the electron beam through the magnetic field.

In a modification such as shown in FIG. 11, it may be mal fixed value ofpeak-to-peak current through the horizontal or vertical coils.

It is to be understood that the word core, as used in the claims, couldbe a magnetic core, a non-magnetic core, or an air core. A support maybe used for winding the toroid, the turns may be glued, and the supporteither retained as part of the core, or removed. Where the core is air,the reference axis then becomes the longitudinal central axis of thecoil which would be in the same position as the core axis 48A and 48Billustrated. Where the core is present, then the longitudinal, orcentral coil axis is the same as the longitudinal central core axis.

It is to be noted from FIGS. 5, l0 and 11 that the the planar extensionsof the tilted turns are non-coplanar with the central core axis, i.e.the planar extensions pass obliquely of the central core axis. I

Whereas it is preferred that at least a pairof coil halves angularlydisposed about the core bejutilized with each coil half having thetilted configuration it may be possible to use a tilted winding on onlyone coil half.

I claim:

1. A deflection coil for use in cathode ray beam deflection yokesincluding a series of turns of wire toroidally disposed on the corewithat least some of the turns being tilted so as to be non-radiallyaligned on the inner surface of the core relative to the longitudinalcentral axis of the coil.

2.- A deflection coil according to claim 1, wherein the tilted turns areso positioned that the imaginary planar extensions thereof, when viewedfrom the front end of the coil, pass obliquely with respect to thelongitudinal central axis of the coil.

3. A deflection coil according to claim 1, wherein the tilted turns areso positioned that the imaginary planar extensions thereof, when viewedfrom the front end of the coil, intersect the longitudinal central axisof the coil.

4. A deflection coil according to claim 3, wherein said tilted turnsinclude more than half of the turns of the coil.

5. A deflection coil according to claim 4, including at least one turn,intermediate the side edges of the coil, said one turn being radiallydisposed so that the imaginary planar extension of the turn, when viewedfrom the front end of the coil, passes through the longitudinal centralaxis of the coil.

6. A deflection coil according to claim 1, wherein the coil includes afront end and a rear end, and wherein the portions of the turns of wireadjacent the front end of the coil, when viewed from the front end ofthe coil, are substantially contiguous throughout substantially theirentire length adjacent the said front end of the coil.

7. A deflection coil for use in cathode ray beam deflection yokes, saidcoil having a front end and a rear end, a series of turns of wiretoroidally wound from the front end to the rear end, the coil 'beingcurved about a longitudinal central axis, the inner diameter of thefront end being greater than the inner diameter of the rear end with theperipheral span of the front end being substantially the same as theperipheral span of the rear end.

8. A deflection yoke for use on a cathode ray beam deflection tube,including a hollow core, at least one coil, said coil including a seriesof turns of wire toroidally disposed axially of the core with at leastsome of the turns being tilted so as to be non-radially aligned on theinner surface of the core relative to the longitudinal central axis ofthe core.

9. A deflection yoke according to claim 8, wherein the tilted turns areso positioned that the imaginary planar extensions thereof, when viewedfrom the front end of the core, pass obliquely with respect to thelongitudinal central axis of the core.

10. A deflection yoke according to claim 9, wherein the tilted turns areso positioned that the imaginary planar extensions thereof, when viewedfrom the front end of the coil, intersect beyond the longitudinalcentral axis of the core. 7

11. A deflection yoke according to claim 9, wherein said tilted turnsinclude more than half of the turns of the coil.

12. A deflection yoke according to claim 8, wherein at least one of thetilted turns is so positioned that a plane passing through the centralaxis of the core and through the point of juncture of the rear end ofthe turn with the inside rear edge of the core is at a greater anglerelative to the vertical than is a plane passing through the centralaxis of the core and through the point of juncture of the front end ofthe turn with the inside front edge of the core.

13. A deflection yoke according to claim 12, wherein at least half ofthe turns of the coil are so tilted.

14. A deflection yoke for use on a cathode ray beam deflection tubeincluding a hollow core, at least one coil, said coil including a seriesof turns of wire wound axially of the core in a toroidal fashion with atleast some of the turns being positioned so that the turns are woundaxially of the core in paths which are longer than the shortest axialtoroidal path for the turn.

15. A deflection yoke for use on cathode ray tubes including a hollowcore, said core being flared in a curved fashion, a coil including aseries of turns wound axially of the core in a toroidal fashion, thecoil having a front peripheral span, a rear peripheral span and anintermediate peripheral span, the intermediate peripheral span beingless in length than either the front peripheral span or the rearperipheral span.

16. A deflection coil according to claim 1, wherein the coil includes afront end, a middle portion and a rear end and wherein the width of themiddle portion is less than the width of the front or rear ends of thecoil.

17. A deflection coil according to claim 1, wherein the tilted turns areso positioned that the imaginary planar extensions thereof, when viewedfrom the front end of the coil, intersect between a confronting innerface of the coil and the longitudinal central axis of the coil.

18. A deflection yoke according to claim 8, wherein the tilted turns areso positioned that the imaginary planar extensions thereof, when viewedfrom the front end of the coil, intersect between a confronting innerface of the core and the longitudinal central axis of the core.

19. A deflection yoke according to claim 18, wherein the tilted turnsinclude more than half of the turns of the coil.

20. A deflection yoke for a cathode ray tube comprising: a core offerromagnetic material having a length, an annular outer surface, anannular inner surface, said inner surface defining a cavity extendinglongitudially through said core from a first aperture at one extreme ofsaid length to a second aperture at another extreme of said length, ahorizontal deflection coil and a vertical deflection coil, one of saiddeflection coils having a plurality of wire turns wound about said core,each of said wire turns circumscribing said inner and outer surfaces andhaving a segment extending through said cavity, said one deflection coilhaving turns of wire which are wound successively in the generaldirection of coil winding advancement separated by a first azimuthalangle 0 at said first aperture and separated by a corresponding secondazimuthal angle 6 at said second aperture, said first and secondazimuthal angles having the relation length, a horizontal deflectioncoil and a vertical deflection coil, one of said deflection coils havinga plurality of wire turns Wound about said core, each of said wire turnscircumscribing said inner and outer surfaces and having a segmentextending through said cavity, said one deflection coil having turns ofwire which are wound successively in the general direction of coilwinding advancement separated by a first azimuthal angle at said firstaperture and separated 'by a corresponding second azimuthal angle 0 atsaid second aperture, said first and second cross sectional areas andsaid azimuthal angles having the relation where A and A are measured insquare inches and 9 and 0 are measured in degrees.

22. A deflection yoke for a cathode ray tube comprising: a core offerromagnetic material having a length, a longitudinal axis, an outerannular surface, an inner annular surface, said inner surface defining acavity extending longitudinally through said core from a first apertureat one extreme of said length to a second aperture of another extreme ofsaid length, said outer surface having linear perimetrical dimensions pand p measured in a plane perpendicular to said axis at points alongsaid surface corresponding to said first and second aperturesrespectively, a horizontal deflection coil-and a vertical deflectioncoil, one of said deflection coils having a plurality of wire turnswound about said core each of said wire turns circumscribingsaid innerand outer surfaces and having a segment extending through said cavity,said one deflection coil having turns of wire separated which arewoundsuccessively in the general direction of coil winding advancementby a first azimuthal angle 6 "at said first aperture and separated -by acorresponding second azimuthal angle 6 atsaid second aperture said firstand second perimetrical dimensions and said first and second azimuthalangles having the relation where p; and p are measured in inches and 6and 0 are measured in degrees.

23. A deflection yoke for a cathode ray tube comprising: a core offerromagnetic material having a length, an outer circular surface, aninner circular surface said inner surface defining a cavity extendinglongitudinally through said core from a first aperture at one extreme ofsaid length to a secondaperture at another extreme of said length,saidouter circular surface having diameters D and D at positions alongthe length of said core corresponding to said first and secondapertures'respectively, a horizontal deflection coil and a verticaldeflectioncoil, one of said deflection coils having a plurality of wireturns wound aboutsaid core, each of said wire turns comprised ofsegments circumscribing said inner and outer surfaces and 'having' asegment extending through said cavity said one deflection coil havingcorresponding segments of turns of wire which are wound successively inthe general direction of coil windings advancement separated by a firstazimuthal angle 6 at said first aperture and separated 'by acorresponding second azimuthal angle 9 at said second aperture, saiddiameters D and D and said first and second azimuthal angles having therelation References Cited by the Examiner UNITED STATES PATENTS2,925,542 2/ 1960 Gethmann 3l7200 3,015,152 '1/1962 Marley 317-2001X3,045,139 7/1962 Lu=tz 317-200 3,117,258 1/1964 Allen 313- 76 BERNARD A.GILHEANY, Primary Examiner. JOHN'F. BURNS, G. HARRIS, JR., AssistantExaminers.

1. A DEFLECTION COIL FOR USE IN CATHODE RAY BEAM DEFLECTION YOKESINCLUDING A SERIES OF TURNS OF WIRE TOROIDALLY DISPOSED ON THE CORE WITHAT LEAST SOME OF THE TURNS BEING TILTED SO AS TO BE NON-RADIALLY ALIGNEDON THE INNER SURFACE OF THE CORE RELATIVE TO THE LONGITUDINAL CENTRALAXIS OF THE COIL.